Use the apostrophe to show possession. Place the apostrophe before the s to show possession in nouns that end in other than s or s sound. Place an apostrophe after a final s to show possession.
Examples:
a boy’s hat; a woman’s hat; one actress’ hat;
a child’s hat;
Ms. Chang’s house; two houses’ doors
Examples:
a boy’s hat; a woman’s hat; one actress’ hat;
a child’s hat;
Ms. Chang’s house; two houses’ doors